Boiler without thermostat

24 Feb 2014
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United Kingdom
I have a new boiler, but I don't have a thermostat yet. I have a Vaillant EcoTech 837.

The boiler isn't running all the time, and my house is a nice temperature all day a night. I set the boiler central heating temperature to 50 and the water to 60. So if I haven't got a thermostat, is the central heating just circulating through the boiler and the boiler just keeping the water at that temp?

I guess the thermostat is for the air temperature and to have more control over this process.

On another note, the boiler is only a week old and already I've topped up the pressure twice. Last night it shut down because the pressure dropped too low. Is this related to the 50 degree temperature I set the water to? The engineer left it at 60 or 65, can't remember which.

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Yes you should have a room stat to comply with current regs.
Go round and check all vents are closed on rads otherwise you may have a leak.
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Thanks for the link. He didn't fit the thermostat because I have a Hive active heating from British Gas on order. Only British Gas can fit those.

So if the pressure is going down, then I definitely have a leak somewhere?

If I had a radiator vent open, wouldn't water be coming out of it?

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